WATCH: 68 year-old knocked out cold by student that could be Obama’s son

Police are investigating a videotaped attack on a substitute teacher at a southwest Philadelphia high school that left him motionless on the ground.

The attack started when a female student sat on a male student’s lap, said 68-year-old substitute English teacher Pewu Johnson.

“He told me ‘get the f*(^ out of my face,'” Johnson said.

The student then threw Johnson to the ground causing him hit his head, school district officials said. Video of the attack shows the teacher motionless in the hallway of the school while students looked on.

“The boy dropped me down with so much force,” said Johnson. “I was out.”

The victim was rushed to the hospital where he was examined and treated for a concussion. His alleged attacker was suspended from school.

“The assault that occurred yesterday is the result of an individual making a dramatically poor choice. The School District does not tolerate this type of behavior and is working with Bartram High School and Philadelphia Police to make sure that the student is discipline and also charged,” said Philadelphia School District spokesperson Fernando Gallard .

This is the third attack on a teacher at the school in less than a month.